There are a couple games by this name, but this is the latest version from a team called Seven Pirates. It's really deep for a mobile game and has absolutely sucked me in. I think I've been playing for a month now, which is about 3 times longer than any mobile game I've ever played!

It's a Fantasy city-builder game, with RPG elements, resource management, a rich PvP game if you want it, and nice guild design.